1. Field of the Invention
The present invention relates to a PCB dipole antenna, and more particularly to a dual-fed PCB dipole antenna used in an electronic device for receiving and/or transmitting electromagnetic signals.
2. Related Art
In the communications field, dipole antennas have been widely used for a long time for effectively receiving and transmitting electromagnetic signals. Most electronic devices use single dipole antennas. Conventionally, a single dipole antenna has three radiation planes, namely an XY-plane, an XZ-plane and a YZ-plane. Generally, only one of these radiation planes has preferred radiation efficiency, and the other radiation planes are disregarded. Moreover, a feeding device of a conventional single dipole antenna is complex and occupies a lot of space. An antenna disclosed in U.S. Pat. No. 4,605,931 utilizes a crossover feeding system. The system comprises pairs of a first feeder apparatus and a second feeder apparatus, one feeder apparatus crossing over the other. Each pair of the crossed first and second feeder apparatuses has a first port and a second port for transmitting a first signal therebetween, and a third port and a fourth port for transmitting a second signal therebetween. The system reduces interaction between signals, and eliminates back feeding of signals. However, the system is too complex to be practically implemented.
Taiwan Patent Application No. 87112281 discloses a circular polarized microstrip antenna that has a short adjustable metal microchip on an edge of a fixed metal microchip. A feed point of the microstrip antenna is on the short adjustable metal microchip or a cross-line thereof which is oriented at 45xc2x0. The metal microchip is installed on a grounding plane. The microstrip antenna has preferred radiation efficiency in the XZ-plane and the YZ-plane. However, the microstrip antenna is also very complex. It requires a large space, and cannot be easily integrated into communications equipment.
Other antennas are disclosed in U.S. Pats. Nos. 4,069,483 and 6,091,366. They all utilize only one of the three radiation planes to provide radiation efficiency.
An object of the present invention is to provide a PCB dipole antenna for placing in an electronic device and having a switch mechanism of dual polarized radiation for making full use of two of the three radiation planes, thereby providing maximum diversity radiation efficiency.
Another object of the present invention is to provide a method of manufacturing an antenna having a switch mechanism of dual polarized radiation for making full use of two of the three radiation planes, thereby providing maximum diversity radiation efficiency.
A further object of the present invention is to provide a PCB dipole antenna which is small and simple in structure, and which reduces manufacturing time and costs.
To achieve the above objects, a PCB dipole antenna in accordance with a preferred embodiment of the present invention for placing in an electronic device includes a first dipole antenna element, a second dipole antenna element, a printed circuit board, a first feeder apparatus and a second feeder apparatus. The first dipole antenna element is perpendicular to the second dipole antenna element. Each of the first and second dipole antenna elements includes two dipole cells respectively disposed on opposite surfaces of the printed circuit board. The first and second dipole antenna elements are fed through the first and second feeder apparatuses respectively. Switching of dual polarized radiation of the PCB dipole antenna is carried out under the control of an external device. This makes full use of two of three radiation planes, and provides maximum diversity radiation efficiency.
These and additional objects, features and advantages of the present invention will become apparent after reading the following detailed description of a preferred embodiment of the invention taken in conjunction with the appended drawings.